Revisiting localized deformation in sand with complex systems

Abstract

Complex systems techniques are used to analyse X-ray micro-CT measurements of grain kinematics in Hostun sand under triaxial compression. Network nodes with the least mean shortest path length to all other nodes, or highest relative closeness centrality, reside in the region where the persistent shear band ultimately develops. This trend, whereby a group of grains distinguishes themselves from the rest in the sample, remarkably manifests from the onset of loading. The shear band's boundaries and thickness, evident from the network communities' borders and essentially constant mean size, provide corroborating evidence of early detection of strain localization. Our findings raise the possibility that the formation and the location of the persistent shear band may be decided in the nascent stages of loading, well before peak shear stress. Grain-scale digital image correlation strain measurements and statistical tests confirm the results are robust. Moreover, the trends are unambiguously reproduced in a discrete element simulation of plane strain compression.

Force chain and contact cycle evolution in a dense granular material under shallow penetration

“…Recent complex network analysis of the interstitial void space and the solid grain phase (e.g. Smart and Ottino, 2008;Tordesillas et al, 2010Tordesillas et al, , 2012Tordesillas et al, , 2013 provide compelling impetus for its future application in solving fundamental problems germane to a broad range of geophysical phenomena, including comminution, dewatering, hydraulic fracturing, fault gouge dynamics, and localised and diffuse mode failure in geomaterials.…”

“…dynamics of force chain evolution, particle kinematics and contact evolution) -against various experimental tests on assemblies of photoelastic disks and on sand (e.g. Tordesillas et al, 2013Tordesillas et al, , 2011.…”

Experimental study of shear bands formation in a granular material

“…Those studies should allow us to observe the influence of different parameters on the shear band formation and study the processes underlying the failure process [4][5][6][7].…”

“…Localization of the deformation and shear band formation in granular materials is an ubiquitous phenomenon which is still very far from being understood [1][2][3][4][5][6][7]. Theoretically the phenomenon is described as a bifurcation [2, 8,9].…”

Topological analysis of tapped granular media using persistent homology

“…This approach can be also used to analyze the evolution of granular media in dynamic situations [9][10][11]. In [12] the topological properties of the network were related to the * sardanza@unav.es † iker@unav.es process of strain localization, which leads to shear banding and material failure. Related with failure is the process of buckling of force chains studied in [13], where the importance of the presence of loops of contacts in the network was revealed.…”